HBM-CTA Red Line Station at Lawrence Ave-converted
CTA Red Line Station at Lawrence Ave.Chicago, IL
Phase I/II/IIIDesign Services
Chicago Transit Authority
Moussa A. Issa, PhD, PE, SEProject Manager(708) 236-0900
H.W. Lochner, Inc.
Key Team Members
Mahmoud A. Issa, Project Engineer
Description of Project
The Red Line Station at Lawrence Avenue consists of two bridges, each carrying two CTA tracks. The southbound structure is a 130′-8″long three-span structure with span lengths of 70′-0″, 31′-3″ and 29′-5″ for Spans 1, 2 and 3, respectively. The northbound structure is a 172′-10″long five-span structure with span lengths of 16′-0″, 41′-2″,45′-0″, 44′-10″ and 25′-8″ for Spans 1 through 5, respectively.
Southbound Span 1 consists of a 9½”-thick reinforced concrete slab supporting approximately 2’-0″-thick ballast. The superstructure consists of rolled stringers with built-up floorbeams and girders. Southbound Spans 2 and 3 consist of an open deck with built-up girders, diaphragms and lateral bracing.
Northbound Span 1 consists of open decking with four built-up girders and lateral bracing. Northbound Span 2 consists of open decking with rolled floorbeams and built-up girders, while Northbound Spans 3 and 4 consist of open decking with rolled girders, lateral bracing and cross-frames. Northbound Span 5 consists of open decking with rolled girders, diaphragms and lateral bracing.
The southbound bridge was originally designed in 1914 for Cooper E-50 loading, and the northbound bridge was designed prior to 1914. Span 5 of the northbound structure was designed in 1993.
Description of Scope
The work included the following for the field inspection and load rating for the northbound and southbound railroad bridges:
- Performed structural field inspection of northbound and southbound railroad bridges, including the timber platform bridging the two structures.
- Performed field measurements of structural bridge elements as needed to supplement available as-built/retrofit plans (required for use as input in rating models).
- Performed structural analysis and rating for the girders, bents and columns for the northbound and southbound structures.
- A bridge rating report was established to present the rating results.
- A schematic framing plan was prepared to show the girders, floor beams, stringers, cross frames, diaphragms and lateral bracing.